A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate. In general, integrated circuits (ICs) comprise a plurality of successive layers that are generated by applying different patterns. In between the application of two successive layers using a lithographic apparatus, a substrate is often processed outside the lithographic apparatus, e.g. in a so-called track apparatus, wherein the wafers undergo various thermal and other treatments. Once a wafer has been processed, it has to be conditioned (in particularly thermally conditioned) before a next exposure process can be applied. In order to ensure that the pattern as applied in a next exposure is applied on the appropriate position relative to an earlier layer, stringent requirements with respect to temperature offset and uniformity have to be met.
In conventional apparatuses, handling robots are applied to transport wafers to be processed and processed wafers to and from a lithographic apparatus. Such handling robots are often equipped with a further functionality such as a thermal conditioning of the wafers that are e.g. received from a track apparatus, prior to transferring these wafers to a lithographic apparatus.
It has been observed that the thermal conditioning of wafers in such conventional handling robots is however insufficient to accommodate for ever increasing requirement such as overlay. In particular with respect to the processing of large wafers such as 450 mm wafers, it is expected that current thermal conditioning of wafers is insufficient to meet future demands with respect to temperature offset and temperature uniformity.